1. Field of the Invention
The present invention relates to a “multipoint” fuel injection device for an annular combustion chamber of a turbine engine such as an airplane turboprop or turbojet.
2. Description OF the Related Art
In known manner, a turbine engine has an annular combustion chamber arranged at the outlet from a high pressure compressor and provided with a plurality of fuel injection devices that are regularly distributed circumferentially at the inlet to the combustion chamber. A “multipoint” injection device has a venturi within which a pilot injector is mounted, the pilot injector being centered on the axis of the venturi and being fed continuously by a pilot circuit, there being a second venturi that is coaxial with the first and that surrounds it. The second venturi has an annular chamber at its upstream end that is fed with fuel by a fuel circuit and that delivers the fuel to injection orifices that open out axially in a downstream direction.
The pilot circuit delivers a continuous flow of fuel that is optimized for low speeds, and the multipoint circuit delivers an intermittent flow of fuel that is optimized for high speeds.
Nevertheless, a major drawback of using the multipoint circuit intermittently is that, under the effect of the high temperatures due to the radiation from the flame in the combustion chamber, such intermittent use leads to clogging or coking of the stagnant fuel inside the multipoint circuit while it is not operating. These phenomena can lead to coke forming in the fuel injection orifices of the multipoint circuit, thereby impeding or reducing the spraying and homogenization of the fuel by the multipoint circuit and thus impeding or reducing the operation of the combustion chamber, or even potentially completely plugging the orifices.
To mitigate that drawback, various different technologies have already been proposed as described in documents EP-A1-2 026 002, EP-A1-2 488 791, EP-A1-2 488 792, and WO-A1-2012/104523.